This invention relates to the dry storage of irradiated nuclear reactor fuel and highly active waste.
When fuel is withdrawn from a nuclear reactor it is highly radioactive and is usually stored for a period of at least 100 days in a cooling pond; the pond water serves to contain the radioactivity and to absorb the heat energy generated by decay of fission products. Pond water cooling is not attractive for long term storage of irradiated nuclear fuel, for example 50 to 100 years, because corrosion of the fuel cladding can occur and there are difficulties in maintaining the pool. An alternative method of storing irradiated nuclear fuel and highly active waste for the long term is to deposit the fuel or waste in concrete cells and cool it by circulating air. Preferably the circulation is effected by a passive system so that maintenance and reliability problems are minimised. To contain the active contamination fully it is advisable to house the nuclear fuel in hermetically sealed canisters of stainless or carbon steel and in British patent specification No. GB 2,096,938A there is disclosed a construction of cells for the dry storage of irradiated nuclear reactor fuel and highly active waste wherein prior to storage the fuel or waste is posted from a preparation chamber into a canister within an adjacent clean chamber, there being a posting facility comprising a tubular port member extending from the preparation chamber into the clean chamber, the tubular port member having a removable closure plug at the end adjacent the preparation chamber and an opening at the other end for embracing the body of a closed canister, the closure plug carrying retractable retention means within the tubular port member for retaining and withdrawing the canister closure into the tubular port member and the retaining means having a hood for sealably masking the outer surface of the canister closure. In operation, the canister sealably connected by the tubular port member forms an extension of the preparation chamber into which the canister closure, after removal from the canister, can be withdrawn with the grab to enable charging of the canister; masking the canister closure avoids contamination of its exterior surface.